scholarly journals Research on the Nonlinear Computer Torque control of the MR Damper Based Above-knee Prosthesis

2019 ◽  
Vol 267 ◽  
pp. 02009
Author(s):  
Qiang Fu ◽  
Chunpeng Pan ◽  
Lei Xu
Keyword(s):  
Feedback Control ◽  
Feedforward Control ◽  
Knee Prosthesis ◽  
Mr Damper ◽  
Torque Control ◽  
Magnetorheological Damper ◽  
Control Law ◽  
Pd Controller ◽  
Control Gain ◽  
And Performance

Aiming at the motion track controlling of the semi-active magnetorheological damper based above-knee prosthesis (MRAKP), according to the LaSalle’s invariant set theorem, a kind of nonlinear compute torque (NCT) control law for the track controlling of the AKMR, is proposed to promote the robustness and performance of the intelligent above-knee prosthesis. The proposed NCT controller includes the feedforward control and the feedback control. The former one is used to compensate the nonlinear terms in the dynamic model of the MRAKP, such as the Coriolis force, the centripetal force, and the gravity. The feedback control, utilizing a nonlinear PD controller, adaptively adjusts the control gain coefficients and reduces the system error. On these bases, numerical simulations on the MRAKPare carried out to analyze the performance of the proposed NCT controller in ADAMS and simulink. For comparing, the track controlling performance of the PD controller and the CT+PD controller are also presented in the paper. Simulation results indicate that the proposed NCT controller for the MRAKP is able to adaptively adjust the control gain coefficients with lower track error and higher robustness than the conventional PD controller and the CT+PD controller.

Vibration Control of a Beam Using the Nearly Optimal Control Algorithm with a Disturbance Force Observer

2001 ◽  
Vol 17 (4) ◽  
pp. 173-177
Author(s):  
Der-An Wang ◽  
Yii-Mai Huang
Keyword(s):  
Optimal Control ◽  
Feedback Control ◽  
Vibration Control ◽  
Feedforward Control ◽  
Active Vibration Control ◽  
Asymptotic Properties ◽  
Control Law ◽  
Flexible Beam ◽  
Active Vibration ◽  
Modal Space

ABSTRACTActive vibration control of a flexible beam subjected to arbitrary, unmeasurable disturbance forces is investigated in this paper. The concept of independent modal space control is adopted. Both the feedforward and feedback control is implemented here to reduce the beam vibration. Because of the existence of the disturbance forces, the feedforward control is applied by employing the idea of force cancellation. A modal space disturbance force observer is then established in this paper to observe the disturbance modal forces for the feedforward control. For obtaining the feedforward and feedback control gains with the optimal sense, the nearly optimal control law is derived, where the modal disturbance forces are regarded as additional states. The vibration control performances and the asymptotic properties of the control law are discussed.

Experimental Analysis and Performance Evaluation of Magnetorheological Damper under High Impact Load

2009 ◽  
Vol 79-82 ◽  
pp. 1387-1390
Author(s):  
Hao Jun Zhou ◽  
Jiong Wang ◽  
Su Xiang Qian ◽  
Xue Zheng Jiang
Keyword(s):  
Performance Evaluation ◽  
Experimental Analysis ◽  
Impact Load ◽  
Mr Damper ◽  
High Impact ◽  
Pressure Response ◽  
Flow Coefficient ◽  
Magnetorheological Damper ◽  
Acceleration Response ◽  
And Performance

Its primary purpose of this study is to provide a comprehensive investigation on its dynamic performance of MR damper under high impact load. A test had been firstly done in order to identify its high shear viscosity of MR fluid. Then, its thermal performance of MR damper under high impact load is analyzed in order to aid its structure design of MR damper intended for weapon recoil mechanisms applications and improve its performance of elimination of heat. Further, Experimental analysis and performance evaluation of MR damper under impact load have been done by numerical simulation and hardware-in-the-loop simulation, including its acceleration response and pressure response of back cavity under different flow coefficient and the same inputting current, and its acceleration response and pressure response of back cavity under the same flow coefficient and different inputting current. Based on these simulation results, the shear-thinning phenomena and its dynamic response under saturated input current are analyzed and some useful conclusions are made. Finally, experimental results indicated that the developed MR damper under high impact load can achieve a good controllability for recoil applications.

scholarly journals Modelling and performance evaluation of energy harvesting linear magnetorheological (MR) damper

2017 ◽  
Vol 36 (2) ◽  
pp. 177-192 ◽  
Author(s):  
Raju Ahamed ◽  
MM Rashid ◽  
MM Ferdaus ◽  
Hazlina B Yusuf
Keyword(s):  
Energy Harvesting ◽  
Output Voltage ◽  
Testing Machine ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Comsol Multiphysics ◽  
Damping Force ◽  
Universal Testing ◽  
Magnetorheological Damping ◽  
And Performance

In this study, an magnetorheological (MR) damper has been designed based on its energy harvesting capability which combines the key benefits of energy generation (reusing lost energy) and magnetorheological damping (controllable damping force). The energy harvesting part has a magnet and coil arrangement to generate energy. A two-dimensional axisymmetric model of the proposed magnetorheological damper is developed in COMSOL Multiphysics where different magnetic field properties are analysed generally by finite element method. Finally, the energy harvesting capability of the proposed magnetorheological damper model is tested by a universal testing machine and observed through an oscilloscope. The maximum induced output voltage was around 0.7 V.

scholarly journals Semi-active control of a nonlinear quarter-car model of hyperloop capsule vehicle with Skyhook and Mixed Skyhook-Acceleration Driven Damper controller

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199952
Author(s):  
Birhan Abebaw Negash ◽  
Wonhee You ◽  
Jinho Lee ◽  
Changyoung Lee ◽  
Kwansup Lee
Keyword(s):  
Resonance Frequency ◽  
Mr Damper ◽  
Active Suspension ◽  
Vertical Displacement ◽  
Suspension System ◽  
Magnetorheological Damper ◽  
Quarter Car Model ◽  
Car Model ◽  
Quarter Car ◽  
And Performance

A suspension system is one of the integral parts of a hyperloop capsule train, which is used to isolate the car-body from bogie vibration to provide a safer and comfortable service. A semi-active suspension system is one of the best candidates for its advantageous features. The performance of a semi-active suspension system relies greatly on the control strategy applied. In this article, Skyhook (SH) and mixed Skyhook-Acceleration Driven Damper (SH-ADD) controlling algorithms are adopted for a nonlinear quarter-car model of a capsule with semi-active magnetorheological damper. The nonlinear vertical dynamic response and performance of the proposed control algorithms are evaluated under MATLAB Simulink environment and hardware-in-loop-system (HILS) environment. The SH controlled semi-active suspension system performance is found to be better at the first resonance frequency and worse at the second resonance frequency than the passive MR damper, but the mixed SH-ADD controlled semi-active suspension system performs better than the passive at all frequency domains. Taking the root-mean-square (RMS) value of sprung mass vertical displacement as an evaluation criterion, the response is reduced by 58.49% with mixed SH-ADD controller and by 54.49% with the SH controller compared to the passive MR damper suspension.

scholarly journals Mountain Bike Rear Suspension Design: Utilizing a Magnetorheological Damper for Active Vibration Isolation and Performance

2020 ◽  
Vol 25 (4) ◽  
pp. 504-512
Author(s):  
Robert Pierce ◽  
Sudhir Kaul ◽  
Jacob Friesen ◽  
Thomas Morgan
Keyword(s):  
Vibration Isolation ◽  
Ride Comfort ◽  
Mr Damper ◽  
Suspension System ◽  
Performance Characteristics ◽  
Magnetorheological Damper ◽  
Control Algorithms ◽  
Mountain Bike ◽  
Rear Suspension ◽  
And Performance

This paper presents experimental results from the development of a rear suspension system that has been designed for a mountain bike. A magnetorheological (MR) damper is used to balance the need of ride comfort with performance characteristics such as handling and pedaling efficiency by using active control. A preliminary seven degree-of-freedom mathematical model has also been developed for the suspension system. Two control algorithms have been tested in this study: on/off control and proportional control. The rear suspension system has been integrated into an existing bike frame and tested on a shaker table as well as a mountain trail. Shaker table testing demonstrates the effectiveness of the damper. Trail testing indicates that the MR damper-based shock absorber can be used to implement different control algorithms. Test results indicate that the control algorithm can be further investigated to accommodate rider preferences and desired performance characteristics.

Use of vent stack temperature as a feedforward variable for dissolver total titratable alkali (TTA) control

TAPPI Journal ◽  
2018 ◽  
Vol 17 (05) ◽  
pp. 261-269
Author(s):  
Wei Ren ◽  
Brennan Dubord ◽  
Jason Johnson ◽  
Bruce Allison
Keyword(s):  
Feedback Control ◽  
Current Practice ◽  
Feedforward Control ◽  
Control Variable ◽  
Indirect Measurement ◽  
Tight Control ◽  
Transfer Lines ◽  
Green Liquor ◽  
Process Dynamics ◽  
Downstream Processes

Tight control of raw green liquor total titratable alkali (TTA) may be considered an important first step towards improving the overall economic performance of the causticizing process. Dissolving tank control is made difficult by the fact that the unknown smelt flow is highly variable and subject to runoff. High TTA variability negatively impacts operational costs through increased scaling in the dissolver and transfer lines, increased deadload in the liquor cycle, under- and over-liming, increased energy consumption, and increased maintenance. Current practice is to use feedback control to regulate the TTA to a target value through manipulation of weak wash flow while simultaneously keeping dissolver density within acceptable limits. Unfortunately, the amount of variability reduction that can be achieved by feedback control alone is fundamentally limited by the process dynamics. One way to improve upon the situation would be to measure the smelt flow and use it as a feedforward control variable. Direct measurement of smelt flow is not yet possible. The use of an indirect measurement, the dissolver vent stack temperature, is investigated in this paper as a surrogate feedforward variable for dissolving tank TTA control. Mill trials indicate that significant variability reduction in the raw green liquor TTA is possible and that the control improvements carry through to the downstream processes.

scholarly journals Evaluation of Process Control Schemes for Sour Water Strippers in Petroleum Refining

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 363
Author(s):  
Chii-Dong Ho ◽  
Yih-Hang Chen ◽  
Chao-Min Chang ◽  
Hsuan Chang
Keyword(s):  
Feedback Control ◽  
Prediction Models ◽  
Feedforward Control ◽  
Absolute Error ◽  
Dynamic Responses ◽  
Control Schemes ◽  
Online Measurements ◽  
Measurement Delay ◽  
Water Feed ◽  
Sour Water

For the sour water strippers in petroleum refinery plants, three prediction models were developed first, including the estimators of sour water feed concentrations using convenient online measurements, the minimum reboiler duty and the corresponding internal temperature at a specific location (Tstage,29). Feedforward control schemes were developed based on these prediction models. Four categories of control schemes, including feedforward, feedback, feedback with external reset, and feedforward-feedback, were proposed and evaluated by the rigorous dynamic simulation model of the sour water stripper for their dynamic responses to the sour water feed stream disturbances. The comparison of control performance, in terms of the settling time, integrated absolute error (IAE) of the NH3 concentration of the stripped sour water and IAE of the specific reboiler duty, reveals that FFT (feedforward control of Tstage,29) and FBA-DT3 (feedback control with 3 min concentration measurement delay) are the best control schemes. The second-best control scheme is FBAT (cascade feedback control of concentration with temperature).

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